It's never too early to make a bad impression.

A cover letter or introductory email is often the first thing a potential employer sees when reviewing a job applicant. It's the first opportunity to impress recruiters and hiring managers and, therefore, the first opportunity to disappoint them. Everything from copy mistakes to inappropriate jokes in a cover letter could derail an application.
Here are the top ten worst things to put on a cover letter...

1. Next to nothing.

While writing something that's too long is a common cover letter mistake, what can be even more damaging is a cover letter that's too short.

Bruce Hurwitz, President of Hurwitz Strategic Staffing, Ltd., a New York-based staffing firm recalls a cover letter he received a few months ago for an entry-level IT sales position. It read simply, "Here's my resume. Call me. (Phone number)."

"I cracked up," Hurwitz says. "This person had only just graduated with a Bachelor's degree. It was ridiculous."

A good cover letter should be somewhere between 200 to 250 words, Hurwitz says, and should answer the question of why a recruiter should look at the resume. "The key is to highlight one success," Hurwitz says. "For example, 'I successfully increased sales 500% over two years, resulting in increased, sustained revenue of $25 million.' Once I read that, I look at the resume."

2. Criticism of a prospective employer.

Thumbtack.com, a San Francisco-based site that connects customers with small business services, asked potential employees to submit in their cover letters feedback about their website. One candidate, a contender for an entry-level position in April, didn't pull any punches.
"The engineering of your site looks lazy and ineffective," the applicant wrote, proceeding to describe the color scheme of the site as "disconcerting to my eyes."
Needless to say, he was not considered for the position, though not before the hiring manager got in some laughs around the water cooler at his expense.
"We forwarded the cover letter to our managers sort of as a joke," says Sander Daniels, co-founder of the site. "It was the most caustic feedback we received. But we responded kindly to him -- we didn't suggest any improvements to him in approaching other employers. We don't see it as our role to counsel failed candidates."
Daniels observed that while many strong candidates turn in well-written cover letters, some have let the demand for engineers get to their heads, as Silicon Valley romances them with six-figure salaries and other job perks.
"Maybe they think they can get away with it -- but in our company, culture is a very important factor." Daniels says. "Even if Facebook's best engineer came to us, we wouldn't hire him if he was a jerk."

3. Personal stories.

While employers are sometimes interested in personal stories, especially if they give some idea about work ethic, it's best to save these stories for the interview, says Lindsay Olson of New York-based Paradigm Staffing, who specializes in recruiting communications and marketing professionals.
"I think my favorite of all time was the salesperson who poetically told me about how he decided to run a marathon, climbed to reach glaciers to have a taste of pure water, ran at heights of 5,000 meters in Peru, and biked down the world's most dangerous road and survived (over 300,000 have not)," says Olson, of a candidate who was applying for a business development position at a recruiting firm in June last year. "All this in his opening paragraph."
If you are asked in an interview about your hobbies and adventures, be prepared with a strong answer, says Olson. "What a (job candidate) likes to do outside of work might show how they are in their job," she says. "As a hiring manager, what you don't like to hear is, 'I just like to sit around at home and read books all day.'"

4. Awkward language.

Rachel Levy, director of marketing at Just Military Loans, a Wilmington, Del.-based personal loan service for military personnel, got a letter last week from a candidate who seemed to be expressing lukewarm interest in an IT analyst position.
"My name is xxx. I am pretty interested in the IT analyst position at Just Military Loans," the letter began.
Levy says she sees many applications, especially for IT jobs, to have grammatical and other language flaws.
"What I've noticed is that there are a lot of people applying to these jobs, for whom English is a second language," Levy says.
"So the connotations of certain words and phrases may not be clear to them. Which is fine, but they should get someone to help word their intentions correctly."
In this case, Levy thinks the applicant meant "very" instead of "pretty," but she'll never know because that applicant didn't get an interview.

5. Someone else's words.

Frank Risalvato, a recruiting officer for Inter-Regional Executive Search Inc., is deluged with cover letters from different candidates that all obviously use the same template from the same career coaches.
"Some of these (cover letters) we see are very obviously not written by the individual," says Risalvato. "We get 15 to 20 of these a month, and it sounds disingenuous and insincere, seeing these cover letters from Seattle one week, Chicago another, and it's all the same style."
Some career experts also warn against the tired stand-by opening lines in a cover letter. "Opening a letter with a passive and clichéd statement such as 'Enclosed please find my resume highlighting my experience and skills that would help your company to grow and succeed,'" is a no-no, says Ann Baehr, certified professional resume writer and president of New York-based Best Resumes. "It's best to use something catchy and more specific such as, "If your company could benefit from the expertise of a hard-charging sales producer with a flawless record of success for closing tier-one Fortune 500 prospects in the healthcare technology market and capturing millions of dollars in revenue, please take a moment to review the attached resume."
If you're uncomfortable with that approach, make your cover letter unique to you with insights about the company you're applying to, advises Darrell Gurney, Los Angeles-based founder of career coaching site Careerguy.com and author of Backdoor Job Search: Never Apply For A Job Again!.
"Put in a note saying something like, 'I've been following your company's progress in the last year and in February and I noticed your company was mentioned in the Journal of such and such,'" Gurney says. "That's the amazing thing about the Internet. You can spend 15 minutes online and look like you've been following them for a year."
Gurney reminds applicants to do their full research on the company if they do get called in for an interview after.Also on FINS.com: How to Negotiate the Salary You Deserve

6. Irrelevant experience.

As noteworthy as an impressive Girl Scout cookies sales record may be, it's not worth trumpeting that experience when trying to break into a field like software sales. Rich DeMatteo, co-founder of Philadelphia-based Social Media Marketing firm Bad Rhino, remembers a candidate who did just that when he was working as a corporate recruiter at a software company.
"I was recruiting for a software sales position and one candidate was sure she was qualified because of her success selling Girl Scout cookies when she was a young girl," DeMatteo says. "I think she was young and didn't realize how important it is to state the right experience. Younger applicants tend to reach for skills, and try to find them anywhere in their life."
Some candidates take it even further, acknowledging they have no relevant skills, but pushing to be hired anyway.
"I read one for an IT analyst position that says, 'Although my qualifications do not exactly match your needs, the close proximity to my home is a big bonus for me,'" Levy of Just Military Loans recalls. "You have a lot of underqualified people just out of college just throwing resumes at the wall, and hoping something sticks."
DeMatteo suggests trying to focus on specific sales figures or experience in relevant projects. "A lot of sales, for instance, is numbers-based. Stick to that."Also on FINS.com: Who to Trust In a Job Search

7. Arrogance.

It's one thing to promote yourself favorably in a cover letter, but watch that it doesn't degenerate into overt bragging.
This is especially true when it comes to ambiguous skills, says Jennifer Fremont-Smith, CEO of Smarterer, a Boston-based tech startup aimed at helping IT applicants improve their resumes.
"People claim to have things like, 'superior Internet skills.' What does that even mean?" says Fremont-Smith. "I saw an application from a Web developer about a month ago where he described himself as a 'rockstar in design tools,' and an 'expert in developer tools.' That kind of inflated language doesn't really tell your employer much about your skills."
Fremont-Smith recommends carefully personalizing your cover letter to the employer and listing the most relevant of skills for the job you want, and why you want it. "The cover letter is the place to tell your story about why it is that you're the right person for the company," she says. "It's about really crafting a narrative that answers the question of why the employer should talk to you."Also on FINS.com: Seasoned Colleagues Can Boost Your Career

8. Wrong company name or wrong cover letter.

Talk about mistakes that are easy to avoid.
"The biggest mistake I see on a regular basis is that candidates either misspell the name of the company or get the name wrong," says Gary Hewing of Houston-based Bert Martinez Communications LLC. "If it's a small misspelling like 'Burt' instead of 'Bert', I'd be willing to overlook that. But the big, unforgivable mistake is when someone copies and pastes a cover letter without the name or address to the correct company. That, to me, is someone who's lazy and not paying attention."
Hewing says sometimes it's hard to tell if a cover letter was meant for a particular job, even if the candidate got the company name and position right, if they talk about disconnected experience without explaining themselves.
"We're a sales organization, but at least twice a month, we'll get a cover letter with someone talking about their banking background instead of sales," says Hewing. "It's a complete disconnect to the job description and it doesn't even explain if the candidate is seeking a career change. It tells me that they're just not paying attention."Also on FINS.com: The Best-Kept Job Interview Secret

9. Cultural preferences.

Job hunting is often compared to dating: It's about finding the right match; and success hinges on staying cool under pressure and masking anxieties to appear confident instead of desperate. But a few candidates take the dating analogy too far, subjecting hiring managers to long lists of personal likes and dislikes in cover letters.
"This one guy wrote the first part of his cover letter talking about his interests like it was an ad for an online dating site," Olson of Paradigm Staffing says, about an applicant trying for a PR job. "He likes all types of music, but 'never got into country.'"
While potentially charming to a possible mate, those tidbits are not helpful in a cover letter.Also on FINS.com: Who to Trust in a Job Search

10. Jokes.

Breaking the ice with humor isn't necessarily a bad idea, but jokes in cover letters are usually a turn-off for busy employers, say recruiters. It might be better to save them for the interview, if they are to be used at all. Olson recalled a candidate for a communications executive position who rubbed an employer the wrong way with an off-color joke.
"She decided in her interview, for some reason, to compare kids to Nazis," says Olson. "She thought she was being funny, but the interviewer happened to be Jewish and didn't think she was very funny."
Recruiters agree that it's best to stick with tried-and-true unfunny, but effective conventional pitches about your education and work experience.
"The thing with trying to be chummy and funny is that you lose credibility," says Gurney of Careerguy.com. "It looks desperate. And the worst thing you can do in job-seeking is looking desperate or needy."Also on FINS.com: How to Negotiate the Salary You Deserve